import java.util.Scanner;
public class Temperature {
    public static void main(String[] args) {
        Scanner scanner=new Scanner(System.in);
        System.out.println("成绩：");
        double temperature=scanner.nextDouble();
        if (temperature>80&temperature<=100){
            System.out.println("A");
        } else if (temperature>70&temperature<=80) {
            System.out.println("B");
        } else if (temperature>60&temperature<=70){
            System.out.println("C");
        } else if (temperature>0&temperature<=60){
            System.out.println("D");
        }
        }
    }
